Microbial Conversion of Oils and Fatty Acids to High-Value Chemicals

Abstract

Microorganisms for the production of high-value chemicals from free fatty acids are provided. The microorganisms comprise genetic mutations that alter fatty acid metabolism. The genetic mutations include a mutation or deletion of a fadR gene in which the FadR enzyme activity is partially or substantially eliminated and a mutation in an atoC gene that provides overexpression of the microorganism's ato operon. Methods of using the microorganisms to produce high-value chemicals are also provided. The high-value chemicals include ethanol, methyl acetate, succinate, gamma-butyrolactone, 1,4-butanediol, acetone, iso-propanol, butyrate, butanol, mevalonate, propionate, ethanolamine and 1,2-propanediol.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Patent Application Ser. Nos. 61 / 007,481, filed on Dec. 13, 2007, and 61 / 189,427, filed on Aug. 19, 2008, both of which are incorporated herein by reference in their entirety.BACKGROUND OF THE INVENTION[0002]The present disclosure generally relates to the metabolic engineering of microorganisms to produce high-value chemicals.[0003]Currently, many high-value chemicals or fuels are typically produced by chemical synthesis from hydrocarbons, including petroleum oil and natural gas. However, as the concerns of energy security, increasing oil and natural gas prices, and global warming escalate, industry is seeking ways to replace chemicals made from non-renewable feedstocks by harsh processes with chemicals made from renewable feedstocks with environmentally friendly processes. In the transportation fuel sector, this trend has led to the growth of the bioethanol and biodiesel industries.[...

AI Technical Summary

Benefits of technology

[0048]The disclosure thus provides a method of converting fatty acids to butyrate, comprising culturing a microorganism comprising reduced fadR expression or function, or increased expression of the fad regulon, increased expression of the atoDAEB genes, increased acetyl-CoA acetyltransferase expression or function, increased 3-hydroxybutyryl-CoA dehydrogenase expression or function, increased crotonase expression or function, a gene encoding butyryl-CoA dehydrogenase, and increased acetyl-CoA:acetoacetyl-CoA transferase or butyrate-acetoacetate CoA transferase expression or function, or a gene encoding phosphotransbutyrylase and a gene encoding butyrate kinase, in a culture medium comprising free fatty acids, monoglycerides, diglycerides, triglycerides, phospholipids, or a combination thereof, thereby converting said free fatty acids to butyrate.

[0049]The present disclosure also provides a method of producing butyrate, comprising culturing a microorganism comprising reduced fadR expression or function, or increased expression of the fad regulon, increased expression of the atoDAEB genes, increased acetyl-CoA acetyltransferase expression or function, increased 3-hydroxybutyryl-CoA dehydrogenase expression or function, increased crotonase expression or function, a gene encoding butyryl-CoA dehydrogenase, and increased acetyl-CoA:acetoacetyl-CoA transferase or butyrate-acetoacetate CoA transferase expression or function, or a gene encoding phosphotransbutyrylase and a gene encoding butyrate kinase, in a culture medium comprising free fatty acids, monoglycerides, diglycerides, triglycerides, phospholipids, or a combination thereof, thereby producing butyrate. Recovery of butyrate can be accomplished by standard techniques known to those of skill in the art, including, but not limited to, recovery from the fermentation broth by ion exchange, crystallization, or precipitation.

Problems solved by technology

While this approach does not have the problems mentioned above, there are still drawbacks.

For example, the maximum theoretical yield (weight basis) of ethanol from a glucose or xylose feedstock for bacterial fermentation is only 0.51, as the required chemical reactions result in a shortage of reducing equivalents.

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